Automatic control mechanism for gramophones and the like



Get. 31, 1939. BURslLL 2,178,199

AUTOMATIC CONTROL MECHANISM FOR GRAMOPHONES AND THE LIKE Filed June 11, 1938 INVENI'OH Hrchzlbald Burdill HI'TOFf/VEY Patented Oct. 31, 1939 (STATES. PATENT OFFICE AUTOMATIC CONTROL MECHANISM FOR GBAMOPHONES AND THE LIKE Archibald Bursill, Burnham, England, assignor 1 to Electric & Musical Industries Limited,

Hay Mid e ex; E g a a comp ny of Great Britain Application June ll, 1938,'Seria1-N0. 213,111

, In Great Britain June 18, 1937 the mechanism constructed in accordance with the invention.

Figure 2 is an end elevation of the mechanism shown in Figure 1 looking towards the left-hand end of Figure 1, and s Figure 3 is a view of the mechanism shown in Figure l with the parts in a different position.

In the drawing, the reference numeral 4 indicates the lever which is intermittently moved. towards and away from a cam 5 formed on a sleeve 6 attached to a boss 'I rotating with the turntable 8, shown in Figure 2, the lever 4 being frictionally coupled with a fork 9 which engages a lug, not shown, depending from the tone arm, also not shown, the lever 4 being capable of an angular movement with respect to the fork 9 between a pair of limiting lugs III and I I. The surface of the lever 4 with which the cam 5 engages is formed by a piece of sound-absorbing or sound-deadening material I 2 which is suitably attached to the end of the lever 4. Extending upwardly from the lever 4 is a lug I 3 which projects above the plane containing the cam 5, as shown in Figure 2, and is adapted to be engaged when an exaggerated movement of the lever 4 occurs by a tripping device, such as a stop I4. The stop I4 is preferably integral with the sleeve 6. The tripping device or stop I4 leads the cam 5 during the rotational movement in the direction of the arrow, shown in Figure 1, and the extent to which the stop I4 projects beyond the cam 5 is such that the movement imparted to the lever 4 from the tone arm during the playing period of the record is insufficient to cause the stop I4 to engage the lug I3 and during this period the cam 5 engages the surface I2 to return the lever 4 to its initial position in known manner. As soon, however, as the tone arm leaves the playing track and an exaggerated movement of the tone arm occurs, the lever 4 is moved a greater distance inwardly towards the axis of the turntable and in such position the lug I3 is moved into a position to be engaged by the stop I4, as shown in Figure 3. Engagement of the stop I4 with the lug I3 stops rotation of the turntable directly or it may serve to move the lever 4 longitudinally in known manner to trip a brake, which in turn stops rotation of the turntable or may actuate a clutch in known manner. The engagement of the stop I4 with the lug I3 may also serve to operate a switch in the circuit of an electric motor rotating the turntable or when applied to a gramophone in which automatic record changing mechanism is provided, engagement of the stop I4 with lug I3 may serve to cause an angular displacement 4 Claims.

This invention relates to automatic control mechanisms for gramophones and the like of the kind in-which an inward movement of the tone arm or arm carrying an electrical reproducing device serves to move a lever into the path of a cam rotated by the turntable drive, the said lever being moved underthe action of the said cam to its originalposition until an exaggerated movement of the tone arm or pick-up arm occurs when due to the consequent increased movement of the said lever the rotation of the turntable is stopped or a brake or a clutch is actuated, initiating if desired subsequent operations such as may be necessary in an automatic record changing machine. Such a control mechanism is disclosed in the specification of British Patent No. 332,004.

Control mechanism of the above kind, while being eficient from the mechanical point of view, is not in one respect satisfactory, since the intermittent engagement of the cam member with the said lever gives rise to a tapping noise which is liable to mar the reproduction of the record.

It is therefore the object of the present invention to provide an improved control means with a view to overcoming this defect.

According to the invention, a control mechanism of the kind referred to is provided in which the surface of said lever with which the cam engages (or the surface of the cam member) is formed of sound-absorbing or sound-deadening material whereby the intermittent engagement of the cam with said lever is rendered less audible, and additional surfaces are provided one of which is carried by said lever and the other of which is rotated by the turntable for co-operation to stop rotation of the turntable when an exaggerated movement of the tone arm occurs. The soundabsorbing or sound-deadening material may be constituted by a piece of leather or other suitable material. In the preferred form of the invention the lever is intermittently moved away from the surface of the cam by the engagement of the cam with sound-absorbing or sound-deadening material carried by the lever, and a lug is provided on said lever and which is engaged when an exaggerated movement of the tone arm occurs by a stop carried in a plane different from that of the cam.

' In order that the said invention may be clearly understood and readily carried into effect, it will now be more fully described with reference to the accompanying drawing in which:

Figure 1 is a plan view of the preferred form of of the said lever above its pivot to cause the initiation of subsequent operations in known manner.

The surface I! of the lever 4 may be mounted in a detachable manner so that it can be readily renewed when required, while the lug on the said lever may be formed by pressing a lug upwardly from the material of said lever. To enable the surface 12 to be adjusted if such should be necessary, it is preferable in this case to employ a disc of material for the surface l2 and to support the disc on the lever 4 by an eccentric screw. In such a construction, the screw may be loosened and the disc rotated for adjustment purposes, tightening of the screw maintaining the disc in its adjusted position. Other means for adjustment may of course be employed.

Where, in the above description, reference has been made to a tone arm, it will be understood that this term is intended to cover the arm carrying the usual electrical reproducing device employed in radio-gramophones.

I claim:

1. In a phonograph, control apparatus comprising a rotatable member, a movable member mounted for movement toward and away from said rotatable member, a cam carried by said rotatable member and rotatable therewith for engagement with said movable member to move it away from said rotatable member upon rotation of said rotatable member, a tripping device also carried by said rotatable member disposed at a difierent elevation from that of said cam, and an element on said movable member adapted to be interposed in the path of rotation of said tripping device to be engaged thereby to effect predetermined control of said phonograph.

2. The invention set forth in claim 1 characterized by the addition of a second element on said movable member arranged thereon to be contacted by said cam during rotation of said rotatable member, and characterized further in that said second element and said cam are both made of a sound-deadening material.

3. The invention set forth in claim 1 charac terized by the addition of a second element on said movable member adjustably arranged thereon to be contacted by said cam during rotation of said rotatable member, and characterized further in that said second element and said cam are both made of a sound-deadening material.

4. The invention set forth in claim 1 characterized in that said tripping device and said cam are so arranged on said rotatable member that said tripping device leads said cam during rotation of said rotatable member.

ARCI-HBALD BURSILL. 

